What is Ubuntu?

The word "ubuntu" is African, meaning 'Humanity to others', or 'I am what I am because of who we all are'. The Ubuntu distribution brings the spirit of Ubuntu to the software world.

Ubuntu GNU/Linux is a free, multi-user, multi-tasking operating system.

• An operating system (OS ) is a set of computer programs that manage the hardware and software resources of a computer. (http://en.wikipedia.org/wiki/Operating_System) All computers have an operating system of some sort. Microsoft Windows, Apple OSX and Ubuntu GNU/Linux are all examples of operating systems.
• Multi-tasking means that the computer can do (or appear to do) several things at the same time. Most modern computers actually only do one thing at a time, but they do them so quickly, and in rapid succession, as to appear to be doing several things at once.
• Multi-user means that more than one person can use the computer, even at the same time. Each person using the computer has their own account, with their own private space to store files and data. Practically speaking, most computers only have one keyboard and mouse attached so only one person can sit at the computer to use it. There are, however, several ways for multiple people to use the computer simultaneously.
• Free, in this context, means "free as in freedom". It is about liberty, and not price. The Free Software Foundation specifies four kinds of freedoms necessary for software to be classified as Free:
  • The freedom to run the program, for any purpose (freedom 0).
  • The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this.
  • The freedom to redistribute copies so you can help your neighbor (freedom 2).
  • The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this.

Ubuntu GNU/Linux satisfies the four freedoms, so is considered Free Software. It is because it is Free Software that FreeGeek Columbus is able to give it to you. You, in turn, are permitted (and encouraged!) to give Ubuntu to your friends and neighbors.

The Ubuntu Desktop

logging in and out
menus
desktop shortcuts
right clicking
taskbars
applets
notifications and pop-ups
shutting down

Working with files

In GNU/Linux, almost everything is represented as a file.  This makes the system (fairly) consistent when dealing with hardware.  Since (most) hardware is represented as a file, the system can usually deal with new hardware without the need for special software.

Files are organized into directories (also called "folders").  GNU/Linux has a standard, well-defined hierarchy for directories, with each directory containing specific files or kinds of files.  The very top of the directory hierarchy is called the root folder, and is represented by a forward slash ( / ). Directories underneath the root folder are called "sub-directories".  Sub-directories can have sub-directories, which can have sub-directories.  You can have many levels of sub-directories.

The organization of directories and files is defined by the Filesystem Hierarchy Standard .  This is a guideline to clearly explain what goes where -- and why -- so that the various version of GNU/Linux will operate in a mostly similar way.  Remember, Ubuntu is just one version of GNU/Linux, there are many others!  The purpose of the FHS is to ensure that what you learn about using Ubuntu will help you use other versions of GNU/Linux, too.

Files and directories have owners.  The owner of files and directories can (usually) make changes to them.  Your user account will usually own the files you create, but will not have access to most of the files on the system.  Most of these files are required for the successful operation of the GNU/Linux operating system, and as a security precaution users are not permitted to modify them.

Most files and directories are visible to everyone -- that is, you can see that they exist, even if you can't necessarily see the contents of them.  Some files and directories, though, are hidden.  This means that they are not displayed to you by default.  Hidden files and folders start with a period.  There are a variety of reasons for having hidden files and directories, and the exact intent of each depends on the location of the item. 

You have one directory over which you have full control.  This is your home directory, and usually resides at /home/<username>, where "<username>" is the account name you used when signing onto the system.  It is in your home directory that most of your files should be stored.  Inside your home directory there are many hidden files and directories.  Most of these contain configuration settings for the various applications you use.  You own these files, and can read, modify and delete them.  Most of the time, though, you don't want to access these files directly, and instead should let the application that created them manage them for you.  It is for this reason that the files are hidden: they're there if you need them, but since you usually don't need to fiddle with them there's no reason to see all of those files on a regular basis.

 
Nautilus file manager
selecting, copying and moving files (p. 107)
bookmarks and file choosers (p. 99)
deleting files

Customizing Ubuntu

login screen
language (p. 100)
wallpaper (p. 101)
themes (p. 101)
screensavers (p. 102

Managing Ubuntu

Ubuntu GNU/Linux is a multi-user system.  Even if you're the only human being to use the computer, there still exists many user accounts defined on the system.  These are used by Ubuntu in a variety of ways.  By having different accounts own different files in the filesystem, the overall security of the computer is enhanced.  Your user account doesn't have permission to modify files owned by the various system accounts, so the core files used by the operating system cannot be compromised by you.  This is one way that GNU/Linux better protects against computer viruses, for example.

User accounts have a variety of properties, the most important of which are the ID and the name.  Your user account name is the name you use when signing into the system.  Your user acccount ID is how the system deals with you internally.  User account names are friendly labels used to make it easy for humans to interact with the system, but the system doesn't particularly care about names, and instead uses numeric IDs.

There exists a user on every GNU/Linux system with an ID of zero.  This user's name is "root".  This is the super-user account.  The root user can do anything on the computer.  Ubuntu has configured the system to disable the root account by default.  This is a security precaution: if someone can log in as the root user (by guessing the root user password, for example), that person can access any files, and make irreperable damage to the system.  Because Ubuntu has disabled this account, no one can log in as root. 

User accounts belong to one or more groups.  Groups are used to orgnanize users.  Permissions can be granted to denied to groups, thereby affecting all the users of that group.  There are a number of pre-defined groups in a basic installation of Ubuntu GNU/Linux, and additional groups can be created as needed.

As mentioned earlier, files have owners.  Files also have group owners.  Permissions can be assigned to files for the owner, the group owner, and for everyone else.  The combination of owner, group owner, and everyone else allows for surprisingly fine-grained control over access to files.

There are three permissions that can be assigned for each file:

• read: access is granted to view the contents of the file or directory
• write: access is granted to change the contents of a file or directory, or to delete it
• execute: access is granted to run the file (if it is a program) or to change into the directory

These three permissions can be applied for each of the file's owner, group, and everyone else.  For example, let's say you're working on your resume.  You don't want anyone else to modify your resume, but you do want other users of the computer to be able to read it.  You would assign yourself read and write permission, and only read permission to everyone else (in this example, the group doesn't matter).

As another example, consider a team working together on a project.  Each member of the team needs to be able to read and write to the team's files, but no one else should be permitted to access the files.  The team would have a group created, and each member of the team would have their user account added to the group.  A directory would be created somewhere, and this directory would have its group owner set to the team's group.  Permissions on the directory would be set for user and group to have read, write, and execute permissions, while everyone else would have no access to the directory.  By denying access to the directory for "everyone", users who are not members of the team's group cannnot access the contents of that directories' files.

adding, changing, and deleting users
adding, changing and deleting printers
keeping up to date (p. 125)
adding and removing applications (p. 118)